7. A VERSION CONTROL
Version control is a system that records
changes to a file or set of files over time so
that you can recall specific versions later.
Even though the examples in this book
show software source code as the files
under version control, in reality any type of
file on a computer can be placed under
8. WHAT IS GIT ?
In 2005, the Linux development community (and in
particular Linus Torvalds) develop their own tool based on
some of the lessons they learned while using BitKeeper.
Some of the goals of the new system were as follows:
◉ Simple design
◉ Strong support for non-linear development
◉ Fully distributed
◉ Able to handle large projects
14. create a new repository
create a new directory, open it and perform a
to create a new git repository.
15. checkout a repository
create a working copy of a local repository by running the command
git clone /path/to/repository
when using a remote server, your command will be
git clone username@host:/path/to/repository
your local repository consists of three "trees" maintained by git. the
first one is your Working Directory which holds the actual files.
the second one is the Index which acts as a staging area and finally
the HEAD which points to the last commit you've made.
18. add & commit
You can propose changes (add it to the Index) using
git add <filename>
git add .
This is the first step in the basic git workflow. To actually commit
these changes use
git commit -m "Commit message"
Now the file is committed to the HEAD, but not in your remote
in its simplest form, you can study repository history using.. git log
You can add a lot of parameters to make the log look like what you want.
To see a very compressed log where each commit is one line:
git log --pretty=oneline
Or maybe you want to see an ASCII art tree of all the branches,
decorated with the names of tags and branches:
git log --graph --oneline --decorate --all
22. pushing changes
Your changes are now in the HEAD of your local working copy. To send
those changes to your remote repository, execute
git push origin master
Change master to whatever branch you want to push your changes to.
If you have not cloned an existing repository and want to connect your
repository to a remote server, you need to add it with
git remote add origin <server>
Now you are able to push your changes to the selected remote server
23. update & merge
to update your local repository to the newest commit, execute
git pull origin master
in your working directory to fetch and merge remote changes.
Branches are used to develop features isolated from each other. The
master branch is the "default" branch when you create a repository. Use
other branches for development and merge them back to the master
branch upon completion.
create a new branch named "feature_x" and switch to it using
git checkout -b feature_x
switch back to master
git checkout master
and delete the branch again
git branch -d feature_x
to merge another branch into your active branch (e.g. master), use
git merge <branch>
in both cases git tries to auto-merge changes. Unfortunately, this is not
always possible and results in conflicts. You are responsible to merge
those conflicts manually by editing the files shown by git.